There are known illumination devices including a light source and a light guide having an incident surface on which light from the light source is incident and an exit surface from which the incident light exits. Such illumination devices are used as a backlight of display devices such as a liquid crystal display device.
The light from the light source is incident on the light-guide and propagates in the light-guide spreading radially therein, and the light attenuates with distance from the light source. Therefore, the luminosity distribution on the exit surface of the light-guide becomes uneven such that, for example, the luminosity becomes stronger in the proximity of the light source and weaker with distance from the light source.
The unevenness in the luminosity distribution causes various problems depending on how the illumination devices are used. For example, if the illumination device is used as a backlight of a display device, the unevenness of the luminosity distribution may deteriorate the display quality.
Each embodiment aims an illumination device which can suppress unevenness in the luminosity distribution and a display device of excellent display quality.